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Re: why TOFD cursor is parabola?

Posted by: Nigel (PID_728), E-mail: ndtservice@yahoo.com, on November 30, 2006 at 09:00 :

In Reply to: Re: why TOFD cursor is parabola? posted by : John , E-mail: jiangyunxi@leepipe.com, on November 30, 2006 at 04:03 :

I have very much appreciated the Platonic dialogue between Yun Xi and Ed G on aspects of phased array. I would not intervene but Ed's last post has a broken link as of my attempt to access it.

So can I (without deep knowledge of the subject) supposition that the wedges will have been machined so that the incident angle of the L-wave from the transducer was approximately 30 degrees (to generate a 45 degree shear-wave in steel). But a focal law of the phased array probe could be constructed to generate a suitable range of angles in the wedge to produce L-waves in the test material. Thus if the PA probe produced a 16 degree beam in the shearwave wedge this would give a 45 degree L-wave in steel. Assuming similar acoustic velocities between the phased-array wedge and the attached "shear-wave" wedge would mean more sound transmission than refraction or reflection at the intrface. Thus the experienced PA focal-law designer would be able to stipulate which incident angles to generate to produce the suitable L-waves in the test material.

Hopefully Ed will return or other experienced people will write to either confirm or refute my supposition and perhaps add some other information.

Thanks guys.

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• Re: why TOFD cursor is parabola? Ed Ginzel

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----------- Start Original Message ----------- : I have very much appreciated the Platonic dialogue between Yun Xi and Ed G on aspects of phased array. I would not intervene but Ed's last post has a broken link as of my attempt to access it. : So can I (without deep knowledge of the subject) supposition that the wedges will have been machined so that the incident angle of the L-wave from the transducer was approximately 30 degrees (to generate a 45 degree shear-wave in steel). But a focal law of the phased array probe could be constructed to generate a suitable range of angles in the wedge to produce L-waves in the test material. Thus if the PA probe produced a 16 degree beam in the shearwave wedge this would give a 45 degree L-wave in steel. Assuming similar acoustic velocities between the phased-array wedge and the attached "shear-wave" wedge would mean more sound transmission than refraction or reflection at the intrface. Thus the experienced PA focal-law designer would be able to stipulate which incident angles to generate to produce the suitable L-waves in the test material. : Hopefully Ed will return or other experienced people will write to either confirm or refute my supposition and perhaps add some other information. : Thanks guys. ------------ End Original Message ------------

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